Background: Incarceration and homelessness are closely related yet studied rarely. This article aimed to study the incarcerated homeless and identify specific vulnerabilities, which rendered them different from the nonincarcerated homeless. It also aimed to describe the homeless population and its significant involvement with the criminal justice and enforcement system.

Methods: Data were derived from the British Columbia Health of the Homeless Study (BCHOHS), carried out in three cities in British Columbia, Canada: the large urban center Vancouver (n = 250), Victoria (n = 150) and Prince George (n = 100). Measures included socio-demographic information, the Maudsley Addiction Profile (MAP), the Childhood Trauma Questionnaire (CTQ) and the Mini International Neuropsychiatric Interview (MINI) Plus.

Results: Incarcerated homeless were more often male (66.6%), were in foster care (56.4%) and had greater substance use especially of crack cocaine (69.6%) and crystal methamphetamine (78.7%). They also had greater scores on emotional and sexual abuse domains of CTQ, indicating greater abuse. A higher prevalence of depression (57%) and psychotic disorders (55.3%) was also observed. Risk factors identified which had a positive predictor value were male gender (p < .001; odds ratio (OR) = 2.8; 95% confidence interval (CI): 1.7–4.4), a diagnosis of depression (p = .02; 95% CI: 1.1–4.4) and severe emotional neglect (p = .02; 95% CI: 1.1–3.2) in the childhood.

Conclusion: Homeless individuals may be traumatized at an early age, put into foster care, rendered homeless, initiated into substance use and re-traumatized on repeated occasions in adult life, rendering them vulnerable to incarceration and mental illness.